Thursday, August 14, 2014

Riley - Week 5; Eelgrass Galore!

July 21st-25th, 2014

This week I was responsible for processing eelgrass samples that we had taken from our trip in Willapa. These were taken during the shell bag sampling. Basically, we cut all of the above ground grass from within the crab corral, and brought them back with us in order to have a dry weight taken (a dry weight is a measure of mass after a sample has been dried, and had all excess liquid is removed from it). We were hoping to find a correlation between the densities of eelgrass within the structured habitats, and compare that to the amount of crabs that settle within those areas. It is possible that crabs don’t simply live an area with eelgrass present, but the amount of eelgrass could factor into this choice as well. Therefore, by finding what the biomass was of each sample that we took and comparing it to the number of crabs we found within that same area, this could give us some idea as to how much covering the crabs prefer to have.
This processing of the eelgrass is a very simple task, however it’s very time consuming. Blade by blade, I had to sort out the Z. japonica, from the Z. marina, from the microalgae. Once all the samples were sorted, each had to be put through a salad spinner to remove any excess liquid. Those individual samples, separated by species and location were placed into pre-measured paper lunch sacs, and measured for a wet weight (the amount of mass of a sample before drying, with water present). The samples were then left in a drying oven for three days, before being measured for dry weight. There was approximately 60 separate samples of eelgrass and algae. The results of this data will be reviewed at a later time.

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